System Sleep and Wireless Mice

I discovered why my system refused to go to sleep.
It should have been obvious.
The sleep command works fine again after I unplug my Kensington "PocketMouse Pro" Wireless mouse.
The little USB dongle apparently just keeps polling for mouse signals, and this interrupts the system whenever it tries to sleep.

Does anyone have a wireless mouse that does NOT prevent hard drive sleep? I really like having an untethered mouse, but don't like the idea of having to unplug the thing every time I want the system to sleep.

Does anyone have a wireless mouse that does NOT prevent hard drive sleep? I really like having an untethered mouse, but don't like the idea of having to unplug the thing every time I want the system to sleep.

I have a Logitech mouseman optical that is OK for all kinds of sleep (the receiver is plugged in the keyboard hub).